In a medium bowl, whisk together sugar, oil, and egg. Whisk in milk, yogurt, and sour cream.

In a large bowl, whisk together flours, 1/4 cup coconut, lemon rind, baking soda, and 1/2 teaspoon salt in a large bowl. Make a well in the center of flour mixture, and add milk mixture to flour mixture, stirring just until moist.

Spoon batter into a 9X5 loaf pan coated with nonstick spray. Sprinkle with remaining 1 tablespoon coconut. Bake for 40-50 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 10 minutes. Remove from loaf pan and cool completely on a wire rack.